The collision happened last Monday on State Route 509 in Tacoma. Luckily, no children were on board at the time, but video from inside the two buses shows how scary it was.
Washington State Patrol troopers say the bus driver hit a pickup truck and another bus before coming to stop.
Nobody was hurt in the crash, but local parents say the incident is a scary reminder of what can happen on any given day.
"I'm not sure -- I'm not sure how to react to that," said parent Cynthia Snyder, whose daughter rides the bus every day.
Troopers ticketed the female bus driver for negligent driving, and now officials from Tacoma Public Schools are investigating whether she was wearing her seat belt properly.
The video clearly shows the driver unbuckling her seat belt, but only the lap belt. The shoulder strap was tucked behind her back the whole time.
Troopers say it's against the law to wear a seat belt in a way it wasn't designed to be worn.
A Tacoma Public Schools spokesperson said it's policy that all bus drivers obey state seat belt laws. A spokesperson for Durham School Services, which contracts with Tacoma schools, said that's their policy as well.
It's unclear if the driver has been suspended.